This invention relates to apparatus for supporting a vibrator such as a car engine on a support body such as a car body. In particular, the invention relates to a control type vibro-isolating support, that can generate controlling force depending on the conditions in which vibration is generated by a vibrator and transmitted to a support body. Abnormality in the vibro-isolating support can be detected for use to make the system more reliable.
A conventional vibro-isolating support of this type is disclosed in Japanese Patent Laid Open No. H.3-24,338, for example. This prior art includes a supporting elastic body interposed between a vibrator and a support body. The elastic body partially defines a fluid chamber, which is filled with fluid. An elastic body supports a movable plate so that the plate can change the volume of the chamber. An electromagnetic actuator includes a permanent magnet and an electromagnet. The actuator can properly displace the movable plate so as to change the volume of the chamber. The volume change elastically deform the elastic body in the expanding direction. This generates controlling force which can cancel the vibration transmitted to the vibro-isolating support.
Specifically, the electromagnetic actuator attracts the movable plate to a specified neutral position, where the supporting force of the elastic body, which supports the plate, balances with the magnetic force of the permanent magnet. Proper adjustment of the magnetic force generated by the electromagnet increases or decreases the magnetic force applied to the plate. It is therefore possible to change the clearance between the plate and the actuator to any value within a possible range, thereby varying the volume of the fluid chamber.
Conventional control type vibro-isolating supports such as mentioned above, however, include no means for detecting their own trouble, degradation or other abnormality. In order for the apparatus to be sufficiently reliable, there is a need to use highly durable members or parts, which make the trouble or degradation offer no problem, but are expensive.